U.S. patent application number 14/754528 was filed with the patent office on 2015-10-22 for electric power control method, electric power control device, and electric power control system.
The applicant listed for this patent is Panasonic Intellectual Property Management Co., Ltd.. Invention is credited to TAKAHIRO KUDOH, SEIYA MIYAZAKI.
Application Number | 20150303690 14/754528 |
Document ID | / |
Family ID | 52279560 |
Filed Date | 2015-10-22 |
United States Patent
Application |
20150303690 |
Kind Code |
A1 |
MIYAZAKI; SEIYA ; et
al. |
October 22, 2015 |
ELECTRIC POWER CONTROL METHOD, ELECTRIC POWER CONTROL DEVICE, AND
ELECTRIC POWER CONTROL SYSTEM
Abstract
An electric power control method according to an aspect of the
present disclosure includes determining a control threshold value
at a start of a demand time period based on a demand target value,
measuring an amount of demand electric power of a customer which
has received an electric power supply from an external power source
and consumed electric power from the start of the demand time
period to an arbitrary time point during the demand time period,
updating the control threshold value based on the measured amount
of demand electric power and the demand target value, and supplying
electric power to the customer from a distributed power source when
an instantaneous value of an electric power consumption of the
customer exceeds the control threshold value during the demand time
period.
Inventors: |
MIYAZAKI; SEIYA; (Hyogo,
JP) ; KUDOH; TAKAHIRO; (Kyoto, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Intellectual Property Management Co., Ltd. |
Osaka |
|
JP |
|
|
Family ID: |
52279560 |
Appl. No.: |
14/754528 |
Filed: |
June 29, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2014/003186 |
Jun 16, 2014 |
|
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|
14754528 |
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Current U.S.
Class: |
700/291 |
Current CPC
Class: |
H02J 3/32 20130101; H02J
2300/24 20200101; H02J 3/381 20130101; H02J 2310/12 20200101; H02J
7/34 20130101; H02J 3/00 20130101; Y02E 10/566 20130101; Y02E 10/56
20130101; Y02E 70/30 20130101; Y02E 10/563 20130101; H02J 2300/30
20200101; H02J 3/387 20130101; H02J 3/383 20130101; H02J 7/35
20130101; G05B 15/02 20130101 |
International
Class: |
H02J 3/00 20060101
H02J003/00; G05B 15/02 20060101 G05B015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 9, 2013 |
JP |
2013-143417 |
Claims
1. An electric power control method comprising: determining a
control threshold value at a start of a demand time period based on
a demand target value; measuring an amount of demand electric power
of a customer which has received an electric power supply from an
external power source and consumed electric power from the start of
the demand time period to an arbitrary time point during the demand
time period; updating the control threshold value based on the
measured amount of demand electric power and the demand target
value; and supplying electric power to the customer from a
distributed power source when an instantaneous value of an electric
power consumption of the customer exceeds the control threshold
value during the demand time period.
2. The electric power control method according to claim 1, wherein
the amount of demand electric power from the start of the demand
time period to a time point of update is measured and the measured
amount of demand electric power is compared with a total amount
which is observed when consumption of electric power with a fixed
demand target value is continued from the start of the demand time
period to the time point of update, if the amount of demand
electric power is smaller than the total amount, the update is
performed by increasing the control threshold value, and if the
amount of demand electric power is greater than the total amount,
the update is performed by reducing the control threshold value
3. The electric power control method according to claim 2, wherein
if the amount of demand electric power is smaller than the total
amount, the update is performed by dividing a value obtained by
subtracting the amount of demand electric power from the total
amount by a time from the time point of update to an end of the
demand time period and adding the value obtained by division to the
control threshold value.
4. The electric power control method according to claim 1, wherein
the update of the control threshold value is repeated at
predetermined intervals during the demand time period.
5. The electric power control method according to claim 1, wherein
an amount of electric power consumption of the customer from the
time point of update to an end of the demand time period is
predicted, and if a total value of the predicted amount of electric
power consumption and the amount of demand electric power from the
start of the demand time period to the time point of update is
smaller than an amount of electric power corresponding to the
demand target value, the control threshold value at a time of the
update is increased and, if the predicted amount of electric power
consumption is greater than the amount of electric power
corresponding to the demand target value, the control threshold
value at the time of the update is reduced.
6. The electric power control method according to claim 1, wherein
the distributed power source is an electricity storage system
provided with at least one storage battery, and if the
instantaneous value of the electric power consumption of the
customer exceeds the control threshold value during the demand time
period, the storage battery is discharged and electric power is
supplied to the customer.
7. The electric power control method according to claim 6, further
comprising: charging the electricity storage system in a period in
which an amount of electric power consumption of the customer is
smaller than the control threshold value when determining that
average demand electric power during the demand time period becomes
smaller than or equal to the demand target value during the demand
time period.
8. The electric power control method according to claim 7, wherein
if the distributed power source is discharged, the distributed
power source is not charged even in a period in which the amount of
demand electric power of the customer is smaller than the control
threshold value in a same demand time period as the demand time
period in which the discharge of the distributed power source is
performed.
9. The electric power control method according to claim 1, wherein
the control threshold value is a threshold value for making an
average value of the amount of demand electric power of the
customer which has received an electric power supply from the
external power source and consumed electric power smaller than or
equal to the demand target value.
10. The electric power control method according to claim 6, wherein
if the amount of demand electric power of the customer exceeds the
control threshold value, the storage battery is discharged by an
amount corresponding to an excess of electric power and, if the
amount of demand electric power of the customer does not exceed the
control threshold value, electric power supplied from the external
power source is supplied to the customer without the storage
battery being charged and discharged.
11. The electric power control method according to claim 1, wherein
the customer is collective housing, a commercial facility, a
communal facility, or a disaster prevention base.
12. The electric power control method according to claim 1, wherein
the external power source is a commercial power source.
13. An electric power control device comprising: one or more
memories; and circuitry operative to: determine a control threshold
value at a start of a demand time period based on a demand target
value; measure an amount of demand electric power of a customer
which has received an electric power supply from an external power
source and consumed electric power from the start of the demand
time period to an arbitrary time point during the demand time
period; update the control threshold value based on the measured
amount of demand electric power and the demand target value; and
supply electric power to the customer from a distributed power
source when an instantaneous value of an electric power consumption
of the customer exceeds the control threshold value during the
demand time period.
14. An electric power control system comprising an electric power
control device and a storage battery that is connected to the
electric power control device via a communication network, wherein
the electric power control device includes one or more memories;
and circuitry operative to: determine a control threshold value at
a start of a demand time period based on a demand target value;
measure an amount of demand electric power of a customer which has
received an electric power supply from an external power source and
consumed electric power from the start of the demand time period to
an arbitrary time point during the demand time period; update the
control threshold value based on the measured amount of demand
electric power and the demand target value; and supply electric
power to the customer from a distributed power source when an
instantaneous value of an electric power consumption of the
customer exceeds the control threshold value during the demand time
period.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present disclosure relates to an electric power control
method, an electric power control device, and an electric power
control system for controlling a distributed power source provided
on the customer's side.
[0003] 2. Description of the Related Art
[0004] In the past, there has been a mechanism of an electric rate
in which contract electric power is determined based on the
magnitude of average electric power (a demand value) in each
interval (demand time period) of a fixed time (for example, 30
minutes) and a basic rate is calculated from this contract electric
power.
[0005] In Japanese Unexamined Patent Application Publication No.
2006-109621, an electric power system including a storage battery,
the electric power system with the aim of reducing the contract
electric power, is disclosed. In this system, a target value of a
demand value is set for a demand time period and, if an
instantaneous value of electric power consumption exceeds the
target value, the storage battery is discharged. By supplementing
the electric power supply of a commercial power source with the
electric power supply from the storage battery, the demand value is
prevented from exceeding the target value.
SUMMARY
[0006] As described above, the contract electric power is
determined by the average electric power in the demand time period,
not the instantaneous value of the electric power consumption; the
technique of Japanese Unexamined Patent Application Publication No.
2006-109621 has a problem of discharge control of the distributed
power source such as the storage battery, the discharge control
being performed even though the value of the average electric power
does not exceed the target value of the demand value.
[0007] One non-limiting and exemplary embodiment provides an
electric power control method that can prevent unnecessary
discharge of a distributed power source while preventing a demand
value from exceeding a target value by discharge of the distributed
power source such as a storage battery.
[0008] In one general aspect, the techniques disclosed here feature
an electric power control method including determining a control
threshold value at a start of a demand time period based on a
demand target value, measuring an amount of demand electric power
of a customer which has received an electric power supply from an
external power source and consumed electric power from the start of
the demand time period to an arbitrary time point during the demand
time period, updating the control threshold value based on the
measured amount of demand electric power and the demand target
value, and supplying electric power to the customer from a
distributed power source when an instantaneous value of an electric
power consumption of the customer exceeds the control threshold
value during the demand time period.
[0009] With the electric power control method according to the
aspect of the present disclosure, it is possible to prevent a
demand value from exceeding a target value by discharge of a
distributed power source while preventing unnecessary discharge of
the distributed power source.
[0010] It should be noted that general or specific embodiments may
be implemented as a system, a method, an integrated circuit, a
computer program, a storage medium, or any selective combination
thereof.
[0011] Additional benefits and advantages of the disclosed
embodiments will become apparent from the specification and
drawings. The benefits and/or advantages may be individually
obtained by the various embodiments and features of the
specification and drawings, which need not all be provided in order
to obtain one or more of such benefits and/or advantages.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a diagram for explaining a problem of the existing
technique;
[0013] FIG. 2 is a configuration diagram of an electric power
supply system;
[0014] FIG. 3 is a configuration diagram of a peak shaving control
device;
[0015] FIG. 4 is a flowchart depicting the flow of processing which
is performed by a controlling section;
[0016] FIG. 5 is a diagram depicting an example of update of a
control threshold value;
[0017] FIG. 6 is a diagram depicting an example of update of the
control threshold value;
[0018] FIG. 7 is a configuration diagram of a peak shaving control
device;
[0019] FIG. 8 is a flowchart depicting the flow of processing which
is performed by the controlling section;
[0020] FIG. 9 is a diagram depicting an example of update of the
control threshold value;
[0021] FIG. 10 is a flowchart depicting the flow of processing
which is performed by the controlling section;
[0022] FIG. 11 is a diagram depicting an example of charge and
discharge; and
[0023] FIG. 12 is a diagram depicting an example of charge and
discharge.
DETAILED DESCRIPTION
<Underlying Knowledge Forming Basis of the Present
Disclosure>
[0024] In the existing technique described in the "Description of
the Related Art" section, control by which a storage battery is
discharged if an instantaneous value of electric power consumption
exceeds a target value of a demand value (hereinafter referred to
as a "demand target value") is performed, but the study conducted
by the inventors has revealed that unnecessary discharge of the
storage battery is performed in specific circumstances.
[0025] That is, even when an instantaneous value of electric power
consumption exceeds the demand target value in a short period in a
demand time period, an average demand value in a longer period
sometimes does not exceed the demand target value. Also in such a
case, in the existing technique, control by which the storage
battery is discharged is performed if an instantaneous value of
electric power consumption exceeds the demand target value, which
results in unnecessary discharge of the storage battery. Such an
example is depicted in FIG. 1.
[0026] In the example of FIG. 1, the storage battery is discharged
if an instantaneous value of electric power consumption exceeds a
demand target value; however, since a demand value (indicated by a
chain double-dashed line) in a demand time period is below the
demand target value even when discharge is not performed, this
discharge is accordingly unnecessary discharge of the storage
battery.
[0027] Since such unnecessary discharge of the storage battery
results in degradation of the storage battery caused by repeated
charge and discharge and can cause a shortage of the amount of
charge sufficient for performing discharge for a high peak or
successive peaks, there is a need to prevent such unnecessary
discharge as much as possible.
[0028] Thus, in an aspect according to the present disclosure, by
updating a threshold value for discharge control of the storage
battery during a demand time period, an attempt to prevent
unnecessary discharge of he storage battery while preventing a
demand value from exceeding a demand target value is made.
Embodiment 1
[0029] Hereinafter, an embodiment will be described with reference
to the drawings.
<Configuration>
[0030] FIG. 2 is a configuration diagram of an electric power
supply system according to the embodiment.
[0031] In an electric power supply system 1, a high voltage
received from a commercial power source 2 is transformed by a
cubicle 6 and supplied to a load 8. Incidentally, the cubicle 6 is
a type of power receiving facility and transforms the received high
voltage. For example, the cubicle 6 transforms received 6600 VAC to
100 VAC or 200 VAC and supplies the resultant voltage to the load
8.
[0032] Moreover, on the customer's side, an electricity storage
system 20 including a storage battery that stores the electric
power which is supplied from the commercial power source 2 is
provided. A peak shaving control device 10 performs charge and
discharge control of the storage battery of the electricity storage
system 20.
[0033] At the time of charge, the electricity storage system 20
converts the alternating-current electric power which is supplied
via the cubicle 6 into a direct current by an AC/DC converter (not
depicted in the drawing) and charges the storage battery. At the
time of discharge, the electricity storage system 20 converts the
direct-current electric power discharged from the storage battery
into an alternating current by a DC/AC converter (not depicted in
the drawing) and supplies the alternating current to the load
8.
[0034] An electric power monitor 4 measures the current and the
voltage flowing through a power-supply line and measures the input
electric power from the commercial power source 2 based on the
measurement result. The electricity storage system 20 receives the
information on the electric power indicating the input electric
power measured by the electric power monitor 4 and uses the
information to prevent a backflow.
[0035] The electric power monitor 7 repeatedly measures a charge
and discharge electric power value of charge and discharge of the
electricity storage system 20 and an electric power consumption
value consumed by the load 8. The measurement results are sent to
the peak shaving control device 10 via the electricity storage
system 20.
[0036] FIG. 3 is a configuration diagram of the peak shaving
control device 10.
[0037] The peak shaving control device 10 includes a demand target
value determining section 12, a charge and discharge plan setting
section 14, and a controlling section 16.
[0038] The demand target value determining section 12 determines a
demand target value.
[0039] The charge and discharge plan setting section 14 sets a
schedule of charge and discharge of the storage battery of the
electricity storage system 20. For example, the charge and
discharge plan setting section 14 sets a schedule by which the
storage battery is charged at night.
[0040] Incidentally, the determination made by the demand target
value determining section 12 and the setting made by the charge and
discharge plan setting section 14 are performed by an operation
which is performed by an operator, for example.
[0041] The controlling section 16 repeatedly acquires the charge
and discharge electric power value of charge and discharge and the
electric power consumption value measured by the electric power
monitor 7 from the electricity storage system 20. If the electric
power consumption value exceeds a control threshold value, the
controlling section 16 gives an instruction to the electricity
storage system 20 to discharge the storage battery.
[0042] Such a storage battery discharge instruction includes the
following types of instruction. [0043] A command value instruction:
a direct instruction about an output value of the storage battery,
such as fixed X [kW] output for 5 minutes. [0044] A flow value
instruction: an instruction to set the flow of demand electric
power, such as instantaneously changing the output of the storage
battery while performing measurement such that a flow value becomes
Y [kW].
[0045] Moreover, the controlling section 16 sets the control
threshold value at the start of a demand time period, calculates
the amount of demand electric power of a customer which has
received the electric power supply from the commercial power source
2 and consumed the electric power until an elapsed time from the
start of the demand time period during the demand time period, and
updates the control threshold value based on the calculated amount
of demand electric power and the demand target value,
[0046] Since this amount of demand electric power is an electric
power consumption value of the customer which has received the
electric power supply from the commercial power source 2 and
consumed the electric power, it is necessary to set the amount of
demand electric power at a value determined in consideration of the
presence or absence of charge.
[0047] That is, if charge and discharge of the storage battery are
not performed (the charge and discharge electric power value is
zero), the electric power consumption value measured by the
electric power monitor 7 is used as it is. If discharge of the
storage battery is performed, in consideration of peak shaving by
discharge, a value obtained by subtracting a discharge electric
power value from the electric power consumption value is used. On
the other hand, if charge of the storage battery is performed, a
value obtained by adding a charge electric power value to the
electric power consumption value is used.
<Operation>
[0048] FIG. 4 is a flowchart depicting the flow of processing which
is performed by the controlling section 16.
[0049] First, the controlling section 16 determines an initial
value of a control threshold value W.sub.T (kW) based on the demand
target value determined by the demand target value determining
section 12 (S40). It is assumed here that this initial value of the
control threshold value W.sub.T (kW) is the same value as the
demand target value, but may be a value obtained by slightly
increasing or decreasing the demand target value.
[0050] Next, the controlling section 16 acquires the electric power
consumption value (kW) measured by the electric power monitor 7
from the electricity storage system 20 and, if the electric power
consumption value (kW) thus acquired exceeds the current control
threshold value W.sub.T (kW) (S41: Yes), the controlling section 16
sends, to the electricity storage system 20, an instruction to
discharge the storage battery by an amount corresponding to the
excess (S42).
[0051] The controlling section 16 repeatedly performs the
processing in S41 and S42 until an elapsed time T (minutes) from
the start of a demand time period reaches an update interval.
[0052] When the elapsed time T (minutes) reaches the update
interval, the controlling section 16 calculates the amount of
demand electric power L.sub.T (kWh) by adding up the demand
electric power values (kW) from the start of the demand time period
to the elapsed time T (minutes), the demand electric power values
(kW) acquired from the electric power monitor 7 (S43).
Incidentally, the demand electric power value is a value obtained
by subtracting the amount of charge and discharge of a distributed
power source from the electric power consumption of the customer.
This makes it possible to give consideration also to the electric
power value of charge and discharge if charge and discharge are
performed.
[0053] Then, the controlling section 16 calculates a new control
threshold value W.sub.T (kW) by using the demand target value D
(kW), the amount of demand electric power LT (kWh), and the elapsed
time T (minutes) and performs update (S44).
[0054] For this calculation, the following equation is used.
W.sub.TD+(D.times.1760-L.sub.T).times.60/(30T) (1)
[0055] In Equation 1, "D.times.T/60" indicates the amount of
electric power consumption observed when the electric power with
the demand target value D (kW) is continuously used for the elapsed
time T (minutes). To convert the amount to the amount of electric
power consumption (kWh) per hour, division by 60 is performed.
Moreover, "30-T" indicates the remaining time obtained by
subtracting the elapsed time T (minutes) from the demand time
period: 30 minutes.
[0056] "(D.times.T/60-.sub.T)" is a difference between the amount
of electric power consumption (D.times.T/60) observed when the
electric power with the demand target value D (kW) is continuously
used for the elapsed time T (minutes) and the amount of demand
electric power L.sub.T (kWh) to the elapsed time T (minutes). If
D.times.T/60>L.sub.T, the second term of Equation 1 becomes
positive and therefore the new control threshold value W.sub.T (kW)
becomes a value which is greater than the demand target value D
(kW). On the other hand, if D.times.T/60<L.sub.T, the second
term of Equation 1 becomes negative and therefore the new control
threshold value WT (kW) becomes a value which is smaller than the
demand target value D (kW).
[0057] As described above, Equation 1 means that, if the amount of
demand electric power L.sub.T (kWh) from the start of the demand
time period to the elapsed time T (minutes) undergoes a transition
at a pace below the demand target value D (kW), by revising the
control threshold value W.sub.T (kW) upwardly, discharge of the
storage battery is prevented from being performed easily, whereby
unnecessary discharge is prevented.
[0058] On the other hand, if the amount of demand electric power
L.sub.T (kWh) from the start of the demand time period to the
elapsed time T (minutes) undergoes a transition at a pace above the
demand target value D (kW), by revising the control threshold value
W.sub.T (kW) downwardly, discharge of the storage battery is
facilitated.
[0059] In addition, based on the difference between the demand
electric power and the demand target value, electric power
consumption with which the demand value will become the demand
target value if the electric power consumption is continuously used
for the remaining time is set as a new control threshold value
W.sub.T (kW). As a result, even when the electric power consumption
value increases after the update of the control threshold value
W.sub.T (kW), by discharging the storage battery under the
condition that the electric power consumption value exceeds the
control threshold value W.sub.T (kW), it is possible to suppress
the demand value so as to be less than or equal to the demand
target value.
[0060] Incidentally, the processing depicted in FIG. 4 is performed
by the demand time period of 30 minutes. That is, when the demand
time period is ended, the controlling section 16 resets the older
control threshold value WT (kW) and performs the processing again
from the processing in S40.
Example 1
[0061] FIG. 5 is a diagram depicting Example 1 of update of the
control threshold value.
[0062] At the start (0:00) of a demand time period (0:00 to 0:30),
the control threshold value is 60 kW, which is the same as the
demand target value. Then, the control threshold value is updated
at intervals of 5 minutes, and, in particular, by the update in
time slots (0:05, 0:10, 0:15) in which the electric power
consumption value is below the demand target value, the control
threshold value increases as compared to the demand target value.
Since the control threshold value is increased in this manner, the
electric power consumption value is below the control threshold
value even in time slots (0:20 to 0:30) in which the electric power
consumption value exceeds the demand target value (60 kW),
discharge of the storage battery is not performed and, in addition
thereto, the consequence result that the average electric power
(demand value) of 30 minutes is below the demand target value is
obtained. As described above, in the example of FIG. 5, it is
possible to prevent unnecessary discharge of the storage battery
while implementing a state in which the demand value does not
exceed the demand target value.
Example 2
[0063] FIG. 6 is a diagram depicting Example 2 of update of the
control threshold value.
[0064] At the start (0:00) of a demand time period (0:00 to 0:30),
the control threshold value is 60 kW, which is the same as the
demand target value.
[0065] The electric power consumption value in the first 15 minutes
(0:00 to 0:15) undergoes a transition at 30 kW which is about half
of the demand target value: 60 kW, and L.sub.T is 30 kW.times.15/60
(h)=7.5 kWh.
[0066] In this case, the controlling section 16 substitutes D=60,
T=15, and L.sub.T=7.5 into Equation 1 and updates the control
threshold value W.sub.T to 90 (kW) by
W.sub.T=60+(60.times.15/60-7.5).times.60/(30-15)
W.sub.T=60+7.5.times.4=90.
<Update of the Control Threshold Value>
[0067] Update of the control threshold value is not limited to the
method using Equation 1 described above and may be any method as
long as the method is a calculation method implementing update by
which, when the amount of demand electric power to a time point of
update is compared with the total amount which is the amount
observed when consumption of the electric power with a fixed demand
target value is continued from the start of a demand time period to
the time point of update, if the amount of demand electric
power<the total amount, the control threshold value is
increased; if the amount of demand electric power>the total
amount, the control threshold value is reduced.
[0068] Moreover, in particular, if the amount of demand electric
power<the total amount, it is preferable to obtain a result of
(the total amount-the amount of demand electric power)/(a time
between a time point of update and the end of the demand time
period) and add the value thus obtained to the control threshold
value.
[0069] By this calculation equation, based on the difference
between the amount of demand electric power from the start of the
demand time period to a time point of update and the demand target
value, electric power consumption with which the demand value will
become the demand target value if the electric power consumption is
continuously used for the remaining time is set as a new control
threshold value W.sub.T. This makes it possible to prevent
unnecessary discharge of the storage battery while suppressing the
demand value so as to be less than or equal to the demand target
value. This calculation equation is useful especially in a case
where an electric power consumption value in the first half of a
demand time period is small as in FIGS. 5 and 6.
<Behavior of the Electricity Storage System>
[0070] A specific example of the behavior of the electricity
storage system observed when the electric power consumption value
exceeds the control threshold value will be described.
[0071] When the storage battery is discharged under the condition
that the electric power consumption value exceeds the control
threshold value W.sub.T (kW), as a method for giving a discharge
instruction to the electricity storage system, there are two ways:
a command value instruction and a flow value instruction.
[0072] In the case of a command value instruction, if the result of
the control threshold value--the demand target value is positive, a
direct instruction to perform discharge by an amount corresponding
to a value of the difference with the rating being set as an upper
limit is given; if the result of the control threshold value--the
demand target value is negative, discharge is not performed.
Incidentally, in some electricity storage systems, consecutive
command value instructions cannot given and only discrete
instructions are possible; in such a case, the amount of discharge
is rounded up.
[0073] In the case of a flow value instruction, the control
threshold value is set as a flow control set value exclusively for
discharge. Here, the flow control exclusively for discharge is
control by which, if the demand electric power exceeds the flow
control set value, control is performed such that the flow becomes
constant by performing discharge by an amount corresponding the
excess, but, since discharge is not performed when the demand
electric power does not exceed the flow control set value, the flow
becomes lower than a flow set value. As similar control, there is
flow control exclusively for charge, which is control by which
charge is performed to the point where the flow set value is not
exceeded. This is used in charge by which the demand target value
is not exceeded, which will be described later.
[0074] The difference between the command value instruction and the
flow value instruction is as follows: in the case of the command
value instruction, the storage battery outputs fixed electric power
until a new control threshold value is set; in the case of the flow
value instruction, the output of the storage battery varies
depending on the electric power consumption of the customer and,
instead, the demand electric power becomes constant.
Embodiment 2
[0075] In Embodiment 2, an attempt to perform appropriate discharge
control of the storage battery is made by predicting the amount of
electric power consumption in a demand time period and performing
update of a control threshold value based on the amount of demand
electric power and the predicted value of the amount of electric
power consumption.
[0076] FIG. 7 is a configuration diagram of a peak shaving control
device 11. The portions identified with the same reference numerals
as those in FIG. 3 are similar to the portions described in FIG.
3.
[0077] The peak shaving control device 11 includes an
in-demand-time-period predicting section 18 that predicts the
amount of electric power consumption in a demand time period.
[0078] FIG. 8 is a flowchart depicting the flow of processing which
is performed by the controlling section 16. The portions identified
with the same step numbers as those in FIG. 4 are similar to the
portions in FIG. 4 and therefore descriptions thereof are
omitted.
[0079] At the start of a demand time period, the
in-demand-time-period predicting section 18 calculates a predicted
value P.sub.T (kWh) of the amount of electric power consumption of
the customer, the amount of electric power consumption to the end
of the demand time period. The calculation method will be described
later.
[0080] Then, the controlling section 16 determines an initial value
of a control threshold value W.sub.T (kW) based on the demand
target value determined by the demand target value determining
section 12 and the predicted value P.sub.T (kWh) (S50).
[0081] Next, the controlling section 16 repeats the processing in
steps S41 and S42 until an elapsed time T (minutes) reaches an
update interval.
[0082] When the elapsed time T (minutes) reaches the update
interval, the controlling section 16 calculates the amount of
demand electric power L.sub.T (kWh) by adding up the demand
electric power values (kW) to the elapsed time T (minutes)
(S43).
[0083] Next, the controlling section 16 updates the predicted value
P.sub.T (kWh) of the amount of electric power consumption of the
customer, the amount of electric power consumption from the elapsed
time T (minutes) to the end of the demand time period (S53).
[0084] Then, the controlling section 16 calculates a new control
threshold value W.sub.T (kW) by using the demand target value D
(kW), the elapsed time T (minutes), the amount of demand electric
power L.sub.T (kWh) to the elapsed time T (minutes), and the
predicted value P.sub.T (kWh) of the amount of electric power
consumption from the elapsed time T (minutes) and performs update
(S54).
[0085] In this calculation, the following equation is used.
W.sub.TD+(D/2-L.sub.T-P.sub.T).times.60/(30-T) (2)
[0086] Incidentally, if T=0 and L.sub.T=0 in Equation 2, the
equation becomes a calculation equation for obtaining the control
threshold value W.sub.T (kW) in step S50.
<Method for Calculating the Predicted Value P.sub.T>
[0087] As a method for calculating the predicted value P.sub.T
(kWh) of the amount of electric power consumption of the customer
to the end of the demand time period, there is a method for
calculating the predicted value P.sub.T (kWh) of the amount of
electric power consumption of the customer to the end of the demand
time period by using the average value of the amounts of electric
power consumption in the past given period.
[0088] For example, if the demand time period is 0:00 to 0:30, when
the predicted value P.sub.T (kWh) is calculated at 0:00,
calculating the predicted value P.sub.T (kWh) by averaging the
amounts of electric power consumption in the past three days in the
same time slot (0:00 to 0:30) as the remaining time slot (0:00 to
0:30) of the demand time period is possible.
[0089] Moreover, if the demand time period is 0:00 to 0:30, when
the predicted value P.sub.T (kWh) is calculated at 0:15,
calculating the predicted value P.sub.T (kWh) by averaging the
amounts of electric power consumption in the past three days in the
same time slot (0:15 to 0:30) as the remaining time slot (0:15 to
0:30) of the demand time period is possible.
[0090] In addition to the methods described above, a calculation
method using a prediction method with consideration given to the
trend of time-series data such as a neural network and an
autoregressive (AR) model and a calculation method using the
external information such as a weather forecast and a forecast
about the temperature may be used.
<Operational Example>
[0091] FIG. 9 is a diagram depicting an example of update of he
control threshold value,
[0092] At the start (0:00) of a demand time period (0:00 to 0:30),
a control threshold value is 80 kW which is greater than a demand
target value. This is because a predicted value in the remaining
time slot (0:00 to 0:30) of the demand time period is a small
value: P.sub.0=20.
[0093] Specifically, L.sub.T and T=0, D=60, and P.sub.0=20 are
substituted into Equation 2 and
W.sub.TD+(D/2-L.sub.T-P.sub.T).times.60/(30-T)
W.sub.T=80,
whereby the control threshold value W.sub.T at the start (0:00) is
80 (kW),
[0094] As described above, since the control threshold value is
increased in the first-half time slot (0:00 to 0:10), the electric
power consumption value is below the control threshold value even
in a time slot (0:00 to 0:10) (indicated by an area which is
diagonally shaded with broken lines in FIG. 9) in which the
electric power consumption value exceeds the demand target value
(60 kW), which eliminates the need for unnecessary discharge of the
storage battery.
<An Object whose Predicted Value is to be Calculated>
[0095] Incidentally, in this embodiment, descriptions have been
given by taking up the electric power consumption of the customer
as an example of an object whose predicted value is to be
calculated, but the example is not limited thereto.
[0096] For example, when a solar battery and a fuel cell are set on
the customer's side, predictions about the outputs of the solar
battery and the fuel cell may be made, The prediction about the
output of the solar battery can be made by using the information on
the weather, the amount of solar radiation, the number of hours of
sunshine, and so forth.
[0097] Moreover, the prediction about the output of a storage
battery which is not an object whose charge and discharge is to be
controlled may be included.
Embodiment 3
[0098] In this embodiment, a method of charge control which is
performed by the controlling section 16 will be described.
[0099] In Embodiment 1 and Embodiment 2, the method of discharge
control has been described; if the power source is a secondary
battery and needs to be charged, when charge is required, there is
a need for a mechanism that performs charge without exceeding a
demand target value also at the time of charge as is the case in
discharge.
[0100] Control which is performed at the time of charge is the same
as that in Embodiments 1 and 2 to the stage of calculation of a
control threshold value, and, by performing charge without
exceeding the control threshold value, it is possible to perform
charge without exceeding the demand target value. On the other
hand, if both charge and discharge are performed in the same demand
time period, such charge and discharge are unnecessary charge and
discharge and have to be prevented. Hereinafter, the control method
therefor will be described.
<Control Method Part 1>
[0101] A first control method will be described by using FIGS. 10
and 11. The aim of this method is to prevent excessive charge and
discharge by reducing an opportunity in which both charge and
discharge are performed in the same demand time period.
[0102] FIG. 10 is a flowchart depicting the flow of processing
which is performed by the controlling section 16.
[0103] A series of processing of FIG. 10 is performed by the demand
time period of 30 minutes. First, at the start of the demand time
period, the controlling section 16 resets a flag indicating that
discharge has been performed in the same demand time period to OFF
(S101).
[0104] Then, the controlling section 16 acquires the electric power
consumption value (kW) measured by the electric power monitor 7
from the electricity storage system 20. If the acquired electric
power consumption value (kW) exceeds the current control threshold
value W.sub.T (kW) (S41: Yes), the controlling section 16 sends, to
the electricity storage system 20, an instruction to discharge the
storage battery by an amount corresponding to the excess (S42) and
turns on the flag (S102).
[0105] If the acquired electric power consumption value (kW) does
not exceed the current control threshold value W.sub.T (kW) (S41:
No), the controlling section 16 gives a charge instruction (S106)
if the time slot is a charge time slot (S103: Yes), the state is
not a fully-charged state (S104: No), and the flag is off (S105:
OFF).
[0106] Since the flag is turned on (S102) if discharge is performed
in the same demand time period, the controlling section 16 does not
give a charge instruction by step S105 even when the other
conditions are then satisfied. Therefore, as depicted in FIG. 11,
if the storage battery is discharged in the same demand time
period, it is possible to prevent the storage battery from being
charged thereafter and reduce the number of times of charge and
discharge. Incidentally, in FIG. 11, an area in which a charge
instruction is not given even when the control threshold value is
not exceeded is indicated by diagonal broken lines.
<Control Method Part 2>
[0107] A second control method will be described by using FIG. 12.
In this method, any one of "a mode in which only discharge of the
storage battery is performed and charge is not performed" (mode 1)
and "a mode in which only charge of the storage battery is
performed and discharge is not performed" (mode 2) is set in
advance and, in the case of mode 1, for example, the controlling
section 16 performs discharge as depicted in FIG. 12 but does not
perform charge irrespective of whether the electric power
consumption value is large or small. Incidentally, in FIG. 12, an
area in which a charge instruction is not given even when the
control threshold value is not exceeded is indicated by diagonal
broken lines.
[0108] As the utilization method of such a mode, a method is
possible in which, for example, the mode is set to mode 1 during
the day in which the amount of usage of electric power is large and
is set to mode 2 in the middle of the night in which the amount of
usage of electric power is small.
<Supplementary Explanation 1>
[0109] While the embodiments of the present disclosure have been
described above, the present disclosure is not limited to the above
descriptions. The present disclosure can be implemented in various
modes for achieving the object of the present disclosure and an
object related thereto or associated therewith and may be as
follows, for example.
[0110] (1) In the embodiments, descriptions have been given based
on the premise that the peak shaving control devices 10 and 11 and
the electricity storage system 20 are different devices, but the
peak shaving control devices 10 and 11 and the electricity storage
system 20 may be configured as one device having their
functions.
[0111] (2) In the embodiments, descriptions have been given based
on the premise that the electric power monitor 7 measures the
electric power consumption value, but the embodiment is not limited
thereto. In place of acquiring the electric power consumption value
from the electric power monitor 7, the electric power consumption
value may be calculated by calculation including a computation by
which the charge and discharge electric power value is subtracted
from the flow value in the electricity storage system 20 (or the
peak shaving control devices 10 and 11). Moreover, calculation may
be performed by performing adding-up processing when necessary.
[0112] (3) In the embodiments, an example in which, at a time point
of update of the control threshold value, the amount of demand
electric power to that point in time is used, such as updating the
control threshold value based on the amount of demand electric
power from 0:00 to 0:15 if the time point of update is 0:15 (see
FIG. 6), has been described.
[0113] However, the example is not limited thereto, and there may
be a slight difference between the points in time due to the
influence of the interval between times at which the controlling
section 16 acquires the demand electric power, the time of
processing required for calculation of demand electric power, and
so forth. For example, if the time point of update is 0:15, the
control threshold value may be updated based on the amount of
demand electric power from 0:00 to 0:14.
[0114] (4) In the embodiments, the unit of demand time period is
set at 30 minutes, but the length of this time can vary depending
on the electric rate structure determined by an electric power
company.
[0115] (5) Examples of the customer of the embodiments include
collective housing such as an apartment building, a commercial
facility such as a store, a communal facility, and a disaster
prevention base. Incidentally, the embodiments can be applied to
all facilities that receive electric power in accordance with an
electric rate plan in which the rates are determined depending on
the maximum demand value. Moreover, the electric power supply
system described in the embodiments is especially useful in a
method (a high-voltage block power-receiving method) in which, in
the case of collective housing, a cubicle is installed in the
collective housing, the high voltage received from the electric
power company is transformed by the cubicle, and the low-voltage
electric power obtained by transformation is supplied to each
housing unit.
[0116] (6) In the embodiments, descriptions have been given by
taking up the commercial power source as an example of the external
power source that performs electric supply from the outside of the
customer and taking up the storage battery as an example of the
distributed power source, but the examples are not limited
thereto,
[0117] The examples of he distributed power source may be a solar
battery, a fuel cell, and so forth. Moreover, as the distributed
power source, other power sources that are installed on the
customer's side may be used.
[0118] (7) The peak shaving control device of each embodiment may
be implemented as large scale integration (LSI) which is typically
an integrated circuit. The circuits may be individually implemented
as one chip or may be implemented as one chip in such a way as to
include all or part of the circuits. The name "LSI" is used here,
but, depending on the difference in the degree of integration, it
is sometimes called an IC (integrated circuit), system LSI, super
LSI, or ultra LSI. Furthermore, the technique of circuit
integration is not limited to LSI, and circuit integration may be
implemented by a dedicated circuit or a general-purpose processor.
A field programmable gate array (FPGA) that is programmable after
LSI is produced and a reconfigurable processor that allows the
connection and settings of circuit cells in LSI to be reconfigured
after the LSI is produced may be used.
[0119] In addition, if the circuit integration technology replacing
LSI appears by the development of the semiconductor technology or
the advent of another derivative technology, it goes without saying
that the functional blocks may be integrated by using that
technology. The application of the biotechnology, for example, may
be possible.
[0120] (8) A program for making a processor perform each control
processing for implementing the functions of the peak shaving
control device depicted in the embodiments can also be distributed
by being recorded on a recording medium or via various
communication paths or the like.
[0121] Such recording media include an IC card, an optical disk, a
flexible disk, ROM, and so forth. The distributed control program
is used by being stored in a memory or the like from which the
control program can be read by the processor, and, as a result of
the processor performing the control program, the various functions
depicted in the embodiments are implemented.
[0122] (9) In the embodiments, descriptions have been given by
taking up the electricity storage system as an example of the
distributed power source, but the example is not limited
thereto.
<Supplementary Explanation 2>
[0123] The embodiments include the following aspects.
[0124] (1) An electric power control method according to the
embodiments is an electric power control method that controls
average electric power in a demand time period so as to be less
than or equal to a demand target value, the method including:
determining a control threshold value at a start of a demand time
period based on a demand target value, measuring an amount of
demand electric power of a customer which has received an electric
power supply from an external power source and consumed electric
power from the start of the demand time period to an arbitrary time
point during the demand time period, updating the control threshold
value based on the measured amount of demand electric power and the
demand target value, and supplying electric power to the customer
from a distributed power source when an instantaneous value of an
electric power consumption of the customer exceeds the control
threshold value during the demand time period.
[0125] (2) The arbitrary time point may be the time point of
update, and, in the updating step, the amount of demand electric
power from the start of the demand time period to the time point of
update may be measured and the measured amount of demand electric
power may be compared with the total amount which is observed when
consumption of electric power with a fixed demand target value is
continued from the start of the demand time period to the time
point of update, if the amount of demand electric power is smaller
than the total amount, update by which the control threshold value
is increased may be performed, and, if the amount of demand
electric power is greater than the total amount, update by which
the control threshold value is reduced may be performed,
[0126] (3) In the updating step, if the amount of demand electric
power is smaller than the total amount, the update may be performed
by dividing a value obtained by subtracting the amount of demand
electric power from the total amount by a time from the time point
of update to the end of the demand time period and adding the value
obtained by division to the control threshold value.
[0127] (4) In the updating step, the update of the control
threshold value may be repeated at predetermined intervals during
the demand time period.
[0128] (5) In the updating step, the amount of electric power
consumption of the customer from the time point of update to the
end of the demand time period may be predicted, and, if the total
value of the predicted amount of electric power consumption and the
amount of demand electric power from the start of the demand time
period to the time point of update is smaller than the amount of
electric power corresponding to the demand target value, the
control threshold value at the time of the update may be increased
and, if the predicted amount of electric power consumption is
greater than the amount of electric power corresponding to the
demand target value, the control threshold value at the time of the
update may be reduced.
[0129] (6) The distributed power source may be an electricity
storage system provided with at least one storage battery, and, in
the supplying step, if the instantaneous value of the electric
power consumption of the customer exceeds the control threshold
value during the demand time period, the storage battery may be
discharged and electric power may be supplied to the customer.
[0130] (7) A charging step of charging the electricity storage
system in a period in which the amount of electric power
consumption of the customer is smaller than the control threshold
value if determination is made that average demand electric power
during the demand time period becomes smaller than or equal to the
demand target value during the demand time period may be
included.
[0131] (8) If the distributed power source is discharged in the
supplying step, in the charging step, the distributed power source
may not be charged even in a period in which the amount of demand
electric power of the customer is smaller than the control
threshold value in the same demand time period as the demand time
period in which the discharge of the distributed power source is
performed.
[0132] (9) The control threshold value may be a threshold value for
making an average value of the amount of demand electric power of
the customer which has received an electric power supply from the
external power source and consumed electric power smaller than or
equal to the demand target value,
[0133] (10) In the supplying step, if the amount of demand electric
power of the customer exceeds the control threshold value, the
storage battery may be discharged by an amount corresponding to the
excess of electric power and, if the amount of demand electric
power of the customer does not exceed the control threshold value,
electric power supplied from the external power source may be
supplied to the customer without the storage battery being charged
and discharged.
[0134] (11) The customer may be collective housing, a commercial
facility, a communal facility, a disaster prevention base, or the
like.
[0135] (12) The external power source may be a commercial power
source.
[0136] (13) An electric power control device according to the
embodiments is an electric power control device that controls
average electric power in a demand time period so as to be smaller
than or equal to a demand target value, the device including one or
more memories; and circuitry operative to: determine a control
threshold value at a start of a demand time period based on a
demand target value; measure an amount of demand electric power of
a customer which has received an electric power supply from an
external power source and consumed electric power from the start of
the demand time period to an arbitrary time point during the demand
time period; update the control threshold value based on the
measured amount of demand electric power and the demand target
value; and supply electric power to the customer from a distributed
power source when an instantaneous value of an electric power
consumption of the customer exceeds the control threshold value
during the demand time period.
[0137] (14) An electric power control system according to the
embodiments is an electric power control system provided with an
electric power control device for preventing average electric power
in a demand time period from exceeding a demand target value and a
storage battery that is connected to the electric power control
device via a communication network, in which the electric power
control device includes one or more memories; and circuitry
operative to: determine a control threshold value at a start of a
demand time period based on a demand target value; measure an
amount of demand electric power of a customer which has received an
electric power supply from an external power source and consumed
electric power from the start of the demand time period to an
arbitrary time point during the demand time period; update the
control threshold value based on the measured amount of demand
electric power and the demand target value; and supply electric
power to the customer from a distributed power source when an
instantaneous value of an electric power consumption of the
customer exceeds the control threshold value during the demand time
period.
[0138] The electric power control method according to the present
disclosure is useful because the electric power control method can
prevent unnecessary discharge of the distributed power source while
preventing the demand value from exceeding the target value by
discharge of the distributed power source.
* * * * *